I got my first FOUR orders yesterday! So exciting and a bit nerve wracking. Here’s the issue. I agreed to make a recipe provided to me by a coworker for her husbands bday. It’s due Monday. The recipe is a chocolate sheet cake that has the icing poured over it as soon as it comes out of the oven. I’ve never made it before but told her I didn’t think it would hold together to turn out straight out the oven. We decided it should be made in a disposable pan and left in it. Not my first choice but it is what it is. Soooo I’ve never baked in disposable pans. Do I need to grease and flour it like I do my regular pans? I don’t wanna make a whole practice cake to try but I don’t want it to stick either. 

I would definitely prepare the pan as you would for any other cake.  Even though you are leaving it in the pan they will still need to be able to cut and remove slices with ease.

yes what freckels said -- those cakes are delicious -- texas sheet cake

Another one who agrees with the above.

the sugar in the cake will hold steady after cooling for five minutes -- you could turn it out at that point and then apply the icing -- I would want to borrow her glass 9x13 to bake it in if I kept it in the pan -- you're making me hungry  I LOVE texas sheet cake

Ditto all of the above, especially the loving Texas Sheet Cake part!